Myocardial remodeling and bioelectric changes in tachycardia-induced heart failure in dogs

In this study, electrical and structural remodeling of ventricles was examined intachycardia-induced heart failure (HF). We studied two groups of weight-matchedadult male mongrel dogs: a sham-operated control group (n=5) and a pacing group(n=5) that underwent ventricular pacing at 230 bpm for 3 weeks. Clinicalsymptoms of congestive HF were observed in both groups. Their hemodynamicparameters were determined and the severity of the HF was evaluated by M-modeechocardiography. Changes in heart morphology were observed by scanning electronand light microscopy. Ventricular action potential duration (APD), as well asthe 50 and 90% APD were measured in both groups. All dogs exhibited clinicalsymptoms of congestive HF after rapid right ventricular pacing for 3 weeks.These data indicate that rapid, right ventricular pacing produces a usefulexperimental model of low-output HF in dogs, characterized by biventricular pumpdysfunction, biventricular cardiac dilation, and non-ischemic impairment of leftventricular contractility. Electrical and structural myocardial remodeling playan essential role in congestive HF progression, and should thus beprevented.